CSI braze-on FD question

[airbonner]

I'm looking at improving my gearing for Deathride. Now have Campy 9s 53/39 rings, 13-26 cassette. Will my FD tab on seat tube accommodate compact crankset? and do I need to change the FD to compact compatible?
Hope my questions make sense.

[Pete Serotta]

Campy or shimano has always worked on mine.

[airbonner]

So all I need is a Campy Compact Crankset. Cool.

[chismog]

My CSI has no braze-on! How'd you get so lucky?

Have done this several times. There's a few issues but you should be OK:

1) Probably need to drop a link out of the chain. Size the chain so the rear derailleur has a smidge of wrap on the small/small combo. Assuming your 26 is working fine right now, your B-screw is probably OK, but you may need to play with that a bit for RD tension/wrap. Note that shortening the chain may create issues with the big/big combo. The old Campy 9s RD has a hard time taking up the wrap from that wide cassette and the compact, in my experience. But leaving the extra link in will likely cause the RD pulley to rub on the chain in the small/small because there is no tension. A 25 on the rear works a little better. You're just going to have to play with it a bit and understand the limitations. Yes, a medium cage RD works better for wrapping a compact and a wider range cassette. I'm assuming you don't want to buy a new one.

2) The front derailleur will need to be dropped. The FD braze hanger *probably* has enough room, but YMMV. It definitely works best to set it up the same as normal, with about 1-2mm clearance between the top of the large chainring teeth and the outer FDcage.

3) A regular FD cage will usually work OK. The issue is that you may drop the chain going from the big to the small chainring, and upshifts aren't quite as snappy. I find it happens when I'm shifting fast and trying to shift the rear at the same time. You can help this with a FD chain watcher thingy of some sort.

After this, you should be riding happily on your new compact! If there's unresolvable or annoying performance problems with the front...

4) A compact or modern FD with a larger inner cage works better. They're pretty cheap these days, you could stick a centaur on there for not much $.

Hope this helps!

[thwart]

I agree with crismog.

I did the very same with a 53/39 + 13/26 9 spd set-up, going to a compact 50/34 on my snow/salt bike. Everything works great; you'll just need to shorten the chain and drop the FD several mm. My short cage RD is coping with everything, and even 'big-big' is not a problem. Best way to shorten the chain, IME, is chain on 'little-little', and then adjust so there's just a bit of tension on it.

And all the parts are Campy's lowest end Mirage, in 9 spd. Well, actually the crank is a UT 10 spd Mirage.

Most 'modern' bikes have enough room on the FD tab to do so, and a rat-tail file is handy for those that don't. Use touch-up paint if you have to go that far...

[airbonner]

I'm aware of chain-wrap issues w/RD. Also plan to use new chain w/new compact chainrings. So I gather that "modern" FDs are compatible w/53 as well as 50t big rings.

[chismog]

I'm aware of chain-wrap issues w/RD. Also plan to use new chain w/new compact chainrings. So I gather that "modern" FDs are compatible w/53 as well as 50t big rings.

Right. Campy made a special FD called the "CT" which had a curve to match the smaller profile of the 50T, but the important difference is really that the inner cage is larger and lower, sort of like a triple FD.

After a couple years Campy dumped the "CT" special compact front derailleur and redesigned a FD that shifts both.

You'll probably have no issues with the regular FD you already have. Just give it a go and see if it works to your standards.

[oldpotatoe]

I'm aware of chain-wrap issues w/RD. Also plan to use new chain w/new compact chainrings. So I gather that "modern" FDs are compatible w/53 as well as 50t big rings.

Campagnolo starting in 2008 and all shimano FDers were standard and compact compatible.